From 3c0a0ba1e40ab25eb9d37773cf380cdf376784be Mon Sep 17 00:00:00 2001
From: "kmillikin@chromium.org"
 <kmillikin@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Tue, 9 Mar 2010 09:56:19 +0000
Subject: [PATCH] Have the flow graph builder collect definitions.

Before computing reaching definitions, the set of all definitions in a
function must be collected and they must be numbered.  Have the flow
graph builder collect definitions for stack-allocated variables into a
list, and implicitly number them with their list index.

Review URL: http://codereview.chromium.org/668257

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4064 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/data-flow.cc | 20 +++++++++++++++++---
 src/data-flow.h  | 12 +++++++++++-
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/src/data-flow.cc b/src/data-flow.cc
index 96acb99..1a0cf1a 100644
--- a/src/data-flow.cc
+++ b/src/data-flow.cc
@@ -431,11 +431,17 @@ void FlowGraphBuilder::VisitAssignment(Assignment* expr) {
   // Left-hand side can be a variable or property (or reference error) but
   // not both.
   ASSERT(var == NULL || prop == NULL);
-  if (prop != NULL) {
+  if (var != NULL) {
+    Visit(expr->value());
+    Slot* slot = var->slot();
+    if (slot != NULL &&
+        (slot->type() == Slot::LOCAL || slot->type() == Slot::PARAMETER)) {
+      definitions_.Add(expr);
+    }
+
+  } else if (prop != NULL) {
     Visit(prop->obj());
     if (!prop->key()->IsPropertyName()) Visit(prop->key());
-  }
-  if (var != NULL || prop != NULL) {
     Visit(expr->value());
   }
   graph_.AppendInstruction(expr);
@@ -492,6 +498,14 @@ void FlowGraphBuilder::VisitUnaryOperation(UnaryOperation* expr) {
 
 void FlowGraphBuilder::VisitCountOperation(CountOperation* expr) {
   Visit(expr->expression());
+  Variable* var = expr->expression()->AsVariableProxy()->AsVariable();
+  if (var != NULL) {
+    Slot* slot = var->slot();
+    if (slot != NULL &&
+        (slot->type() == Slot::LOCAL || slot->type() == Slot::PARAMETER)) {
+      definitions_.Add(expr);
+    }
+  }
   graph_.AppendInstruction(expr);
 }
 
diff --git a/src/data-flow.h b/src/data-flow.h
index adad5f9..0e05b7e 100644
--- a/src/data-flow.h
+++ b/src/data-flow.h
@@ -385,7 +385,12 @@ class JoinNode: public Node {
 // traversal orders as a byproduct.
 class FlowGraphBuilder: public AstVisitor {
  public:
-  FlowGraphBuilder() : global_exit_(NULL), preorder_(4), postorder_(4) {}
+  FlowGraphBuilder()
+      : global_exit_(NULL),
+        preorder_(4),
+        postorder_(4),
+        definitions_(4) {
+  }
 
   void Build(FunctionLiteral* lit);
 
@@ -406,6 +411,11 @@ class FlowGraphBuilder: public AstVisitor {
   ZoneList<Node*> preorder_;
   ZoneList<Node*> postorder_;
 
+  // The flow graph builder collects a list of definitions (assignments and
+  // count operations) to stack-allocated variables to use for reaching
+  // definitions analysis.
+  ZoneList<AstNode*> definitions_;
+
   DISALLOW_COPY_AND_ASSIGN(FlowGraphBuilder);
 };
 
-- 
2.7.4